Ear to the track

An unobtrusive sensor that collects and immediately transmits data might help the UK’s athletes in their quest for medals at London’s 2012 Olympic games.

The cufflink-sized sensor, designed to cause no discomfort or adversely affect an athlete’s aerodynamics, is worn behind the ear like a Bluetooth headset and collects data about posture, stride length, step frequency and acceleration by responding to shock waves travelling through the body.

This information is then wirelessly transmitted to a visual display on a handheld device or laptop used by a coach at the trackside.

Currently under development at Imperial College London, the sensor is a vast improvement on current body sensors used to measure athletic performance.

These are sometimes cumbersome to wear, which affects technique and performance and makes the information they produce less useful. Also, frequently the information cannot be monitored in real-time.

According to project leader, Prof Guang Zhong Yang, the sensor is inspired by the semicircular canals of the inner ear, which play a key role in controlling motion and balance.

Posture and gait

‘The sensor has a MEMS accelerometer, which detects the information that is naturally picked up by the semicircular canals,’ explained Yang. ‘It’s able to pick up things like posture and gait because the bones in the spine are a good conductor of high-frequency waves.’

With the sensor’s current design, information about the body is converted from an analogue to digital signal and processed through a tiny microprocessor on the sensor. That data is then wirelessly transmitted out through a small antenna.

‘The drawback is that digital technology is very good but tends to be power hungry,’ said Yang. ‘Right now the sensor node is digitising analogue signals, processing them and sending them out — but it might be better to just use the analogue signal and do the processing on the node itself. You can bypass a few steps and cut down the power. These are some things we are working on.’

Yang has gained recognition over the years for pioneering research in the field of Body Sensor Networks (BSN). The primary motivation behind this research is to enable continuous measurements of physical and physiological parameters of users without restricting activity.

Yang said that in his work over the years he frequently found success when he used the human body for design inspiration, and this sensor is no different. ‘In bio-engineering and engineering in general, there is a lot you can learn from Mother Nature,’ he said.

The sensor is undergoing trials with elite UK athletes, and the developers believe it will be entering widespread use within 12-18 months, initially with sprinters but eventually with rowers and other athletes.

‘This sensor will be able to fine-tune an athlete’s performance,’ said Yang. ‘It will be able to monitor sprinters during their crouching start into their peak acceleration, and will help them maintain that acceleration and work towards their final push. It will be able to pick up a lot of useful information like shock wave transmission and step frequency, which allows you to fine tune your running gait during sprinting.’

In addition to sports training, Imperial’s BSN technology could be used in healthcare applications. With the use of miniaturised sensors, patients suffering from ailments such as cardiac disease or episodic and possibly life threatening events like a surge in blood pressure could be continuously monitored. Abnormalities such as this are important but can go undetected when using current techniques because these events occur only infrequently and may never be recorded objectively.

The sensor is currently undergoing clinical trials with out-patients who have recently undergone minimally invasive surgery.

Apart from the ‘real-world’ applications, Yang said this technology could soon make its way into the virtual gaming world.

The Imperial team has already developed a prototype ski-ing simulation game that responds to a user’s body movements.

‘We’ve had a lot of fun playing with that,’ said Yang.

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